A handheld electrochemical bacterial sensor based on multifunctional composite hydrogels and DNA biomimetic nanowalls for accurate detection of Porphyromonas gingivalis

•The novel MFCHgel shows superior conductivity, electrical activity and adhesion.•The MFCHgel solves the thorny problem of electrode-modified material detachment.•The DBNWs significantly enhance the electrical impedance response of bacteria.•An advanced handheld electrochemical bacterial sensor was developed.•The Hebs can be utilized for the point-of-care testing of pathogenic bacteria. Porphyromonas gingivalis (Pg) is not merely one of the important periodontal pathogens, but also exhibits a profound and intimate connection with various systemic diseases, such as cancer, cardiovascular disease, and Alzheimer’s disease. Hence, a handheld electrochemical bacterial sensor (Hebs) is developed for point-of-care testing of Pg in saliva based on an enhanced personal glucose meter platform. In the Hebs, a novel multifunctional composite hydrogel (MFCHgel) is prepared with outstanding conductivity, electrical activity, adhesion and modifiability. In particular, its superior adhesion effectively addresses the inherent issue of electrode-modified material being prone to detachment while ensuring excellent conductivity, which is extremely beneficial for the stability of biosensor. In addition, by assembling DNA biomimetic nanowalls (DBNWs), the surface negative charge and steric hindrance of Pg are enhanced significantly, leading to a remarkable improvement in the electrical impedance response of Pg. Based on their cooperation, the Hebs is capable of effectively detecting Pg within the range of 10 to 1 × 107 CFU/mL, with an impressive limit of detection as low as 6 CFU/mL. Significantly, Hebs exhibits remarkable accuracy in analyzing 40 clinical saliva samples and offers distinct advantages in terms of time consumption and portability as compared to the ELISA kit. This work successfully develops a Hebs for point-of-care testing of Pg, thereby presenting a novel perspective for the advancement of portable bacterial detection devices.